This study has as its objective an evaluation of the efficacy of argon laser photocoagulation in the treatment of subretinal neovascularization in presumed ocular histoplasmosis, senile macular degeneration, and idiopathic subretinal neovascularization. Documentation of the natural history of all three diseases is also a goal. More specifically, the study is intended to determine whether obliteration of extrafoveal choroidal neovascular membranes using photocoagulation is helpful in preserving visual acuity in eyes marked by one of the diseases.